The invention pertains to a pressure transducer arrangement for the measuring of fluid pressure, particularly for invasive blood pressure measuring.
EP 0,124,308 A2 shows a pressure transducer arrangement with three components, namely a single use pressure transducer, a holding element and a connecting cable to a monitor. The actual pressure measuring element, which is connected to a chamber that can be charged with the fluid pressure to be measured, is encapsulated in a housing of the pressure transducer. The pressure measuring element is fitted with electronic connectors that can be inserted into matching connectors of the holding element. The holding element also has a housing that is shaped appropriately to hold the housing of the pressure transducer. The matching contacts on the holding element housing are connected to the cable. After use, the pressure transducer housing can be manually removed from the holding element and can be replaced with a new pressure transducer housing.
A similar pressure transducer arrangement is known from DE 4,400,941 that also consists of three components, namely a pressure transducer, a cable with a connector and a holding element to hold the pressure transducer and the connector.
The pressure transducer has a housing with two chambers, a fluid channel and two fluid connections. One of the connections is connected to the vascular system of a patient and the other one to an infusion bottle, which permits an infusion of e.g. physiological saline solution for the prevention of blood coagulation in the conducting system. A measuring instrument is positioned in the housing chamber, which is located between the two connections, and the instrument is fixed on a substrate and is pressure-connected to the fluid channel. Further, strip conductors are provided on the substrate that are connected to the pressure measuring element and with other electronic components of a measuring circuit. The substrate and the strip conductors are extended into the interior of the second housing chamber. There, the ends of the strip conductors form connectors that can be accessed through an opening in the housing wall. The plug is configured to match the housing opening and the contacts, and contains matching contacts for the contacts that are connected to the cable wires. On its top, the holding element contains holding rails into which the pressure transducer can be inserted.
When measuring blood pressure, the pressure transducer is attached to the holding element and the plug is inserted in such a way that the contacts touch the matching contacts. A blood pressure that is present in the pressure transducer is measured by the pressure measuring element and transformed into an electronic signal that is transferred to a monitor through the cable. Frequently, during surgery or with patients in intensive care, several pressures have to be measured simultaneously, which requires the use of several pressure transducers. Accordingly, the said holding elements are configured in a modular fashion so that several holding elements, each with one pressure transducer, can be positioned alongside each other. Separate cables lead from these holding elements to the monitor, one for each pressure transducer. The multitude of cables and hoses renders the measuring arrangement rather confusing and creates the danger that mix-ups may occur when changing the pressure transducers and that nursing personnel may trip over the cables.
Further, the pressure transducers are regularly exchanged for each patient, disposed of and replaced with new ones, while the holding elements and cables are reused (compare DE 4,317,985 A1). The hoses must be disconnected and connected to the new pressure transducers when changing the pressure transducers. In this process, blood or infusion fluid may be spilled on the new pressure transducer or on the holding elements.
Pressure transducers of the type described here are customarily equipped with a Wheatstone bridge, with one branch of the bridge containing a pressure-sensitive resistor. Normally, during function testing, this branch is jumped with a defined resistor. The monitor will usually display a test value of 100 mm/Hg. Switching in this resistor is accomplished by means of a key, usually located on the monitor, on the pressure transducer itself (DE 4,400,941) or together with a shunt resistor on the cable (EP 0,366,651 C2 and U.S. Pat. No. 4,603,574). In the event that the key is located on the monitor or on the cable, the key is reusable even if the pressure transducer is discarded after use.
A pressure transducer arrangement is known from DE 29,506,589 U1 that features several so-called "pressure domes" that are each connected to the patient and to the infusion bottle and are disposed of after one use. The pressure domes are mounted on reusable holding elements that are positioned alongside each other in a modular fashion. Each holding element features a reusable pressure measuring element with a pressure transfer membrane that interacts with a pressure transfer membrane on the outside of the corresponding pressure dome. In this case, too, a cable goes out from each pressure measuring element, which leads to the aforementioned problems.